CN105375798B - Adaptively sampled circuit, primary side feedback constant-voltage system and switch power supply system - Google Patents
Adaptively sampled circuit, primary side feedback constant-voltage system and switch power supply system Download PDFInfo
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- CN105375798B CN105375798B CN201510831047.7A CN201510831047A CN105375798B CN 105375798 B CN105375798 B CN 105375798B CN 201510831047 A CN201510831047 A CN 201510831047A CN 105375798 B CN105375798 B CN 105375798B
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Abstract
One adaptively sampled circuit of present disclosure and the primary side feedback constant-voltage system using the circuit, the circuit include：Peak reference voltage generation module, computing module, ramp voltage generation module, comparison module and pulse generation module；Peak reference voltage generation module is used to generate current peak reference voltage；Computing module is used to current peak reference voltage carrying out scale operation, and exports sample reference voltage；Ramp voltage generation module is used to produce ramp voltage；Comparison module is used for by sample reference voltage compared with ramp voltage, when ramp voltage is more than sample reference voltage, exports the sample identification signal of a high level, otherwise, exports a low level sample identification signal；Pulse generation module is used to receive sample identification signal, and produces a narrow pulse signal in the rising edge of sample identification signal, so that changed using the sampling time automatic follow current peak change of the switch power supply system of adaptively sampled circuit.
Description
Technical field
The present invention relates to electronic applications, more particularly to adaptively sampled circuit, primary side feedback constant-voltage system and Switching Power Supply
System.
Background technology
Fig. 1 is a kind of conventional primary side feedback constant-voltage system.As illustrated, D1~D4 is rectifier bridge, C1 is input electricity
Hold, alternating voltage is filtered into DC voltage (Vbus) after rectifier bridge and electric capacity C1；Rst is to start resistance, and one end is electrically connected
Vbus is connected to, the other end is electrically connected to chip pin VCC；C2 is the electric capacity for the pin VCC for being connected to chip IC 1；During startup, electricity
The electric current flowed through on resistance Rst charges to electric capacity C2, when the pin VCC of chip IC 1 voltage reaches the threshold voltage of chip setting
When, chip starts, and one switching signal of output is with driving FET Q1；IC1 is control chip, and Q1 is power switch pipe, and T1 is
Transformer, Rcs are primary side winding current sampling resistor, and the electric current flowed through in primary side winding, which flows through, starts resistance Rcs, starts resistance
Rcs one end is electrically connected to the CS pins of chip IC 1, other end ground connection, the voltage of the CS pins of chip IC 1 be proportional to primary side around
Group electric current；First resistor R1 and second resistance R2 is the divider resistance of auxiliary winding voltage, and FB is the feedback pin of chip IC 1,
To reflection output voltage indirectly；5th diode D5, the 4th resistance R4 and the 4th electric capacity C4 are primary side RCD absorbing circuits；The
Six diode D6 are auxiliary side diodes, and the 7th diode D7 is secondary side diode, and the 3rd electric capacity C3 is output capacitance.
According to Fig. 1, although feedback pin FB electrical potential energy reflects output voltage indirectly, because the current potential shows
For pulse voltage, the FB waveforms of discontinuous mode as shown in Figure 2, wherein GATE is the waveform of the GATE pins of chip IC 1, and FB is
The waveform of the FB pins of chip IC 1, ip are transformer primary side winding current waveform, and is is transformer secondary winding current waveform.
To sum up, FB is the reflection output voltage within the demagnetization time (Tdemag) of a cycle, then needs sample circuit demagnetizing
The voltage signal sometime gathered on FB pins in time.
Constant pressure sample circuit inside existing primary side feedback constant-voltage system control chip is sampled using the set time mostly,
The timing since turning off primary side power switch pipe, is sampled after the set time to feedback voltage (FB).Although compare appearance
Set time sample circuit easily is realized, but set time sample circuit has the shortcomings that certain：Primary side feedback constant-voltage system is
Low noise and no-load power consumption as small as possible are realized, in different loads, chip internal is generally set primary current peak value
For difference.When heavier loads, primary current peak value is higher；When light load, primary current peak value is relatively low.As shown in Figure 3：
For the constant-voltage system of primary side feedback, discontinuous mode is usually operated at, it is secondary for different primary current peak values (Ipp)
Side current peak also equal proportion change (Isp), it then follows following equation：Isp=Nps*Ipp, wherein, Nps is the former secondary turn ratio.If
Sampled using the set time (Tsh), for different primary current peak values, the electric current that is flowed through in sample point secondary side diode
(i.e. secondary current is) is different, causes the pressure drop (V in sample point secondary side diodeD) different, it is Δ VDDifference, should
ΔVDVoltage differences can add on the output voltage, Vo=Vs-VD, wherein, Vs is that transformer secondary voltage (passes through feedback control loop, Vs
Keep constant), Vo is output voltage, during different loads, VDVariant, then, output voltage also can be variant, and then exports permanent
Pressure precision will necessarily reduce, and for the relatively low system of output voltage, the difference can influence bigger.
Therefore, need badly and a kind of new adaptively sampled circuit and the primary side feedback constant-voltage system using the circuit are provided, with
Solve the above problems.
The content of the invention
In order to solve the above problems, there is provided a kind of adaptively sampled circuit and the primary side feedback constant pressure system using the circuit
System, it uses adaptively sampled mode so that sampling time automatic follow current peak change and change, with it is existing fixed when
Between sample mode compare, can greatly reduce in addition eliminate different loads when sample point secondary side diode voltage drop it
Difference, so that output voltage precision is improved.
According to an aspect of of the present present invention, there is provided a kind of adaptively sampled circuit, including：One peak reference voltage generates mould
Block, a computing module, a ramp voltage generation module, a comparison module, a pulse generation module；Wherein, the peak reference
Voltage generation module is used to generate a current peak reference voltage；The computing module and the peak reference voltage generation module
It is connected, for the current peak reference voltage to be carried out into scale operation, and exports a sample reference voltage to the comparison
Module；The ramp voltage generation module is used to produce a ramp voltage, and exports to the comparison module；The relatively mould
Block is used for by the sample reference voltage compared with the ramp voltage, when the ramp voltage is more than the sample reference
During voltage, the sample identification signal of a high level is exported, when the ramp voltage is less than or equal to the sample reference voltage
When, export a low level sample identification signal；The pulse generation module is used to receive sample identification signal, and is sampling
The rising edge of id signal, a narrow pulse signal is produced, so that the sampling of the switch power supply system using adaptively sampled circuit
Time automatic follow current peak change and change.
In one embodiment of this invention, the computing module includes：One operational amplifier, a first resistor and one second
Resistance；The first input end of the operational amplifier receives the current peak of the peak reference voltage generation module with reference to electricity
Pressure, the second input of the operational amplifier are respectively electrically connected to one end of first resistor and one end of second resistance；It is described
The other end of first resistor is electrically connected to the output end of the operational amplifier；The other end ground connection of the second resistance.
In one embodiment of this invention, current peak reference voltage amplification proportional to the sample reference voltage
Relation.
In one embodiment of this invention, current peak reference voltage diminution proportional to the sample reference voltage
Relation.
In one embodiment of this invention, the ramp voltage generation module includes：One first fixed bias current source, one
Switch control unit, a first switch, a fixed voltage source and one first electric capacity；Wherein described first fixed bias current source leads to
Cross the first switch and be electrically connected to the fixed voltage source, and the first fixed bias current source is electrically connected to described first
One end of electric capacity, the other end ground connection of first electric capacity；The switch control unit is used to export a switch controlling signal, with
Control the on or off of the first switch；When the first switch is turns on, the voltage of one end of first electric capacity
Equal to the voltage of the fixed voltage source, when the first switch is turns off, the first fixed bias current source is to described
First electric capacity is charged, and produces an electricity equal with the voltage of the fixed voltage source in one end of first electric capacity
Press the ramp voltage for starting point and rising.
In one embodiment of this invention, when the switch controlling signal is high level, the first switch is conducting；
When the switch controlling signal is low level, the first switch is shut-off.
In one embodiment of this invention, the ramp voltage generation module includes：One first fixed bias current source, one
Switch control unit, a first switch and one first electric capacity；Opened by described first in wherein described first fixed bias current source
Close electrically, and the first fixed bias current source is electrically connected to one end of first electric capacity, first electric capacity
The other end is grounded；The switch control unit be used for export a switch controlling signal, with control the conducting of the first switch or
Shut-off；When the first switch is turns on, the voltage of one end of first electric capacity is equal to zero, when the first switch is pass
When disconnected, the first fixed bias current source is charged to first electric capacity, and is produced in one end of first electric capacity
A raw no-voltage is starting point and the ramp voltage risen.
In one embodiment of this invention, when the switch controlling signal is high level, the first switch is conducting；
When the switch controlling signal is low level, the first switch is shut-off.
In one embodiment of this invention, the comparison module includes：One comparator, for by the sample reference voltage
Compared with the ramp voltage, the sample identification signal of varying level is exported according to comparative result.
According to another aspect of the present invention, there is provided a kind of printed circuit board (PCB), the printed circuit board (PCB) include above-mentioned adaptive
Answer sample circuit.
According to another aspect of the present invention, there is provided a kind of primary side feedback constant-voltage system, it includes a rectifier bridge, a filtering mould
Block, one start power supply module, a drive module, a primary side absorption module, a primary current sampling module, a voltage sample mould
Block, a voltage changing module, a secondary output module and a load；The input of wherein described rectifier bridge electrically connects with city, is used for
It is direct current by AC rectification, and is sent to the filtration module；The filtration module is used to be filtered direct current；Institute
State startup power supply module to be connected with the filtration module, supplied for starting the drive module, and to the drive module
Electricity；The drive module is connected with the primary side absorption module, for carrying out Isobarically Control, wherein the drive module includes one
Isobarically Control chip and a FET, the Isobarically Control chip include above-mentioned adaptively sampled circuit and loop control mould
Block；The primary side absorption module is used to limit the ceiling voltage that the FET of the drive module drains when off；It is described
Primary current sampling module is connected with the drive module, for obtaining primary side winding electric current；The voltage changing module and the original
Side absorption module connection, the mutual conversion for the voltage x current between primary side, secondary, auxiliary side winding；The secondary output
The voltage that module is used to export a vice-side winding is to the load；The voltage sample module is connected to the drive module, uses
In demagnetization time internal feedback voltage of the acquisition in a cycle, and it is sent to the adaptively sampled electricity of the drive module
Road；The loop back control module is used for the narrow pulse signal for receiving the adaptively sampled circuit, and utilizes the burst pulse
Feedback voltage signal is carried out sampling holding signal and error is amplified, while controls the grid of the FET of the drive module
Pole, with formed the voltage close loop of whole loop control, and then cause the primary side feedback constant-voltage system sampling time automatically with
Change with current peak and change.
In one embodiment of this invention, the Isobarically Control chip further comprises：One demagnetization detection module, a load
Current conversion module and a reference voltage generation module；Wherein, the demagnetization detection module is connected to the voltage sample module,
To obtain the demagnetization time；The load current modular converter is connected to the demagnetization detection module, to according to the demagnetization
Time and the relation of work period, the ratio-voltage of load current is proportional to generation；The reference voltage generation module connection
To the load current modular converter, for producing current peak reference voltage according to ratio-voltage, and it is sent to described adaptive
Answer the peak reference voltage generation module of sample circuit.
In one embodiment of this invention, when loading different, by setting the fixation in the adaptively sampled circuit
The current value of bias current sources, the ramp voltage generation module the first electric capacity capacitance and the computing module
The resistance value of one resistance and second resistance, so that the difference of the voltage drop of the 7th diode in the secondary output module is zero.
According to another aspect of the present invention, there is provided a kind of switch power supply system, the switch power supply system include above-mentioned
Adaptively sampled circuit and a loop back control module, the loop back control module are defeated for receiving the adaptively sampled circuit institute
The narrow pulse signal gone out, and sampling holding and error amplification are carried out to feedback voltage signal using the narrow pulse signal, with
The control of whole loop is realized, and then causes the sampling time automatic follow current peak change of the switch power supply system and becomes
Change.
It is an advantage of the current invention that by using adaptively sampled circuit and the primary side feedback constant pressure system using the circuit
System, it is possible to achieve sampling time automatic follow current peak change and change, can compared with existing set time sample mode
The difference of the voltage drop of sample point secondary side diode during greatly reducing or even eliminate different loads, so that output voltage
Precision is improved；And from power switch shutdown moment until the delay between sampled point is that electric capacity is charged by current source
Realize, whole circuit realiration is simple and easy.
Brief description of the drawings
Fig. 1 is a kind of circuit connection diagram of conventional primary side feedback constant-voltage system；
Fig. 2 is the waveform diagram of the primary side feedback constant-voltage system shown in Fig. 1；
Fig. 3 is the schematic diagram of primary current peak value of the primary side feedback constant-voltage system in the case of different loads shown in Fig. 1；
Fig. 4 is sampling time of the invention automatic follow current peak change and the operation principle schematic diagram that changes；
Fig. 5 is the circuit connection diagram of an embodiment of the adaptively sampled circuit of the present invention；
Fig. 6 is the respective waveforms figure of the internal signal of the adaptively sampled circuit shown in Fig. 5；
Fig. 7 is the circuit connection diagram of another embodiment of the adaptively sampled circuit of the present invention；
Fig. 8 A and Fig. 8 B are schematic diagram of the present invention using the primary side feedback constant-voltage system of the adaptively sampled circuit；
Fig. 9 is the structural representation of the loop back control module of primary side feedback constant-voltage system of the present invention.
Embodiment
Primary side feedback constant pressure system to adaptively sampled circuit provided by the invention and using the circuit below in conjunction with the accompanying drawings
The embodiment of system elaborates.
Fig. 3 is the schematic diagram of primary current peak value of the primary side feedback constant-voltage system in the case of different loads, wherein, solid line
It is the less waveform of primary current peak value；Dotted line is the larger waveform of primary current peak value.From the figure 3, it may be seen that for primary side feedback
Constant-voltage system for, discontinuous mode is usually operated at, for different primary current peak values (Ipp), secondary current peak value
Equal proportion changes (Isp), it then follows following equation：Isp=Nps*Ipp, wherein, Nps is the former secondary turn ratio.If use the set time
(Tsh) sample, for different primary current peak values, electric current (the i.e. secondary current that is flowed through in sample point secondary side diode
Is it is) different, cause the pressure drop (V in sample point secondary side diodeD) different, it is Δ VDDifference, Δ VDVoltage differences
It can add on the output voltage, Vo=Vs-VD, wherein, Vs is transformer secondary voltage (by feedback control loop, Vs keeps constant),
Vo is output voltage, during different loads, VDVariant, then, output voltage also can be variant, and then it is inevitable to export constant pressure precision
It can reduce, for the relatively low system of output voltage, the difference can influence bigger.
Then, the present invention proposes a kind of adaptively sampled circuit, when it sets sampling automatically according to primary current peak value
Between, rather than the fixed setting sampling time, to solve the above problems.That is, the system by using adaptively sampled circuit
Sampling time automatic follow current peak change and change, greatly reduce even eliminate in different primary current peak values,
The difference of caused voltage drop in secondary side diode, so as to improve output voltage precision.
Sampling time of the invention shown in Figure 4 automatic follow current peak change and change operation principle signal
Figure, wherein ip are primary current waveform, and is is secondary current waveform, VDFor secondary side diode voltage waveform.Dotted line and solid line point
Not Dui Ying two kinds of different loads when waveform, current peak corresponding to dotted line waveform is higher than current peak corresponding to solid line waveform.
Tsh1 is sampling time delay corresponding to solid line waveform, and Tsh2 is sampling time delay corresponding to dotted line waveform.
The electric current that sample point flows through secondary side diode is shown below：
Wherein, Is_sh is sample point secondary side diode electric current, and Tdemag is the demagnetization time, and Tsh is the sampling time, Nps
For the former secondary turn ratio, Ipp is primary side inductive current peak.Wherein Tdemag expression formula is as follows：
Ls is secondary inductance sensibility reciprocal, VOFor output voltage, VDFor secondary side diode pressure drop.
(2) are substituted into (1) to obtain：
For the system of a determination, Nps, VO, VDAnd Ls is fixed value, therefore can extend as inferior from (3)
Formula：
Sample point secondary side diode current expression is corresponding to solid line：
Sample point secondary side diode current expression is corresponding to dotted line：
If eliminate the difference of secondary side diode voltage drop corresponding to different primary current peak values, i.e. VD1=VD2=VD, then
Need to meet following equation：
Is_sh1=Is_sh2 (4)
Above-mentioned equation (3-1) and equation (3-2) are substituted into equation (4) again, can be obtained：
If Tsh1 and Tsh2 meet the relation of above-mentioned equation (5), can eliminate secondary corresponding to different primary current peak values
The difference of side diode drop.
Therefore, based on above-mentioned principle, the present invention proposes a kind of adaptively sampled circuit, explanation as detailed below.
Shown in Figure 5, in one embodiment of the present invention, a kind of adaptively sampled circuit includes：Including a peak value
Reference voltage generation module 510, a computing module 520, a ramp voltage generation module 530, a comparison module 540, a pulse
Generation module 550；Wherein, the peak reference voltage generation module 510 is used to generate a current peak reference voltage Vcs_
ref；The computing module 520 is connected with the peak reference voltage generation module 510, for current peak reference is electric
Press Vcs_ref to carry out scale operation, and export a sample reference voltage Vsh_ref to the comparison module 540；The slope
Voltage generation module 530 is used to produce a ramp voltage Vramp, and exports to the comparison module 540；The comparison module
540 are used for by the sample reference voltage Vsh_ref compared with the ramp voltage Vramp, when the ramp voltage
When Vramp is more than the sample reference voltage Vsh_ref, the sample identification signal (i.e. Tsample signals) of a high level is exported,
When the ramp voltage Vramp is less than or equal to the sample reference voltage Vsh_ref, the low level sampling mark of output one
Know signal；The pulse generation module 550 is used to receive sample identification signal, and in the rising edge of sample identification signal, production
A raw narrow pulse signal (i.e. sampled signal), so that followed automatically using the sampling time of the Switching Power Supply of adaptively sampled circuit
Current peak changes and changed.Wherein, the concrete structure of the primary side feedback constant-voltage system will be described in detail below.
Each module of adaptively sampled circuit or the structural relation of circuit are will be explained in detail below.
Wherein, the computing module 520 includes：One operational amplifier, a first resistor R1 and a second resistance R2；It is described
The first input end of operational amplifier receives the current peak reference voltage of the peak reference voltage generation module 510, described
Second input of operational amplifier is respectively electrically connected to first resistor R1 one end and second resistance R2 one end；Described first
The resistance R1 other end is electrically connected to the output end of the operational amplifier；The other end ground connection of the second resistance R2.
In the present embodiment, the current peak reference voltage Vcs_ref and the sample reference voltage Vsh_ref into
Scaling relation.Under normal circumstances, because the current peak reference voltage Vcs_ref is smaller, generally hundreds of millivolts, it is
Make the sampling time more accurate, it is preferable that by operational amplifier to obtain the sample reference voltage of suitable magnitude
Vsh_ref.Certainly, in other embodiments, the current peak reference voltage Vcs_ref and the sample reference voltage
Vsh_ref can also form scale smaller relation by operational amplifier.
In the present embodiment, it is preferable that the ramp voltage generation module 530 includes：One first fixed bias current
Source Ib, a switch control unit 531, a first switch S1, a fixed voltage source Vsource and one first electric capacity C1；Wherein institute
State the first fixed bias current source and the fixed voltage source Vsource, and described are electrically connected to by the first switch S1
One fixed bias current source Ib is electrically connected to one end of the first electric capacity C1, the other end ground connection of the first electric capacity C1；Institute
State switch control unit 531 be used for export a switch controlling signal, to control the on or off of the first switch S1；Work as institute
When stating first switch S1 to turn on, the voltage of one end of the first electric capacity C1 is equal to the electricity of the fixed voltage source Vsource
Pressure, when the first switch S1 is turns off, the first fixed bias current source Ib charges to the first electric capacity C1,
And it is starting point to produce a voltage equal with the voltage of the fixed voltage source Vsource in one end of the first electric capacity C1
And the ramp voltage Vramp risen.Wherein it is possible to when to set the switch controlling signal be high level, the first switch S1
For conducting；When the switch controlling signal is low level, the first switch S1 is shut-off.
The comparison module 540 includes：One comparator, for by the sample reference voltage Vsh_ref and the slope
Voltage Vramp is compared, and the sample identification signal of varying level is exported according to comparative result.The pulse generation module 550
According to the sample identification signal of varying level, and at the rising edge of sample identification signal, corresponding narrow pulse signal is produced
(i.e. sampled signal), so that the sampling time automatic follow current peak of the primary side feedback constant-voltage system using adaptively sampled circuit
Value changes and change.
That is, according to existing known equation Vcs_ref=Ipp*Rcs, it is known that current peak reference voltage Vcs_ref
It is proportional to primary current peak I pp.In the present embodiment, by the way that current peak reference voltage Vcs_ref progress ratio is put
Greatly, sample reference voltage Vsh_ref is produced；When switch controlling signal Gate_ON is low level, the first fixed bias current source
Ib charges to the first electric capacity C1, and it is starting point and rising to produce a voltage equal with the voltage Vsource of fixed voltage source
Ramp voltage Vramp, ramp voltage Vramp produces adopting for varying level compared with sample reference voltage Vsh_ref
Sample id signal, then the processing of the pulse generation circuit (Timer_OneShot) through extra pulse generation module 550, obtain corresponding
Narrow pulse signal (i.e. sampled signal SH).
The respective waveforms figure of the internal signal of adaptively sampled circuit shown in Figure 6.Because current peak is with reference to electricity
Press Vcs_ref and sample reference voltage Vsh_ref it is directly proportional to primary current peak I pp, ramp voltage Vramp be with
The voltage equal with the voltage of the fixed voltage source is starting point, and in upward status, until sample reference voltage Vsh_ref,
Now reach sampled point, and then cause linear to Tsh and Ipp in the time of the sampled point from first switch S1 shutdown moments
Relation.
Circuit diagram according to Fig. 4 obtains following formula：
In adaptively sampled circuit (wherein, the adaptively sampled circuit can be included in an Isobarically Control chip)
C1, Vsource, Ib, R1 and R2 are fixed value, and for the system (such as primary side feedback constant-voltage system) of determination, Rcs is also solid
Definite value, it is as follows sampling time expression formula corresponding to two different primary current peak values can be obtained from (6) formula：
Corresponding primary current peak I pp1, is obtained：
Corresponding primary current peak I pp2, is obtained：
Above-mentioned equation (6-2) both sides are subtracted into equation (6-1) simultaneously, the relation for obtaining Tsh1 and Tsh2 is as follows：
Above-mentioned equation (5) and formula (7) are contrasted, (wherein, the adaptively sampled circuit can include in adaptively sampled circuit
C1, Ib, R1 and R2 can be set in an Isobarically Control chip IC 1, as shown in Figure 8 A and 8 B) so that：
(wherein, if the adaptively sampled circuit can be included in an Isobarically Control chip IC 1 to adaptively sampled circuit
It is interior) in C1, Ib, R1 and R2 set and must meet (8) formula, then foregoing circuit is achieved that to eliminate different primary current peak values corresponding
Secondary side diode voltage drop difference.That is, when loading different, by setting consolidating in the adaptively sampled circuit
Determine the current values of bias current sources, the ramp voltage generation module the first electric capacity capacitance and the computing module
The resistance value of first resistor and second resistance, so that the secondary of the primary side feedback constant-voltage system using the adaptively sampled circuit
The difference of the voltage drop of the 7th diode in output module is zero, and the difference of voltage drop herein is zero to refer to be equal to zero, or approximation etc.
In zero.So, compared with set time sample mode used by prior art, present embodiment can be reduced greatly even
The difference of sample point secondary side diode voltage drop when eliminating different loads, so that output voltage precision is improved.
Shown in Figure 7, the present invention also provides a kind of another embodiment of adaptively sampled circuit.Preferably
In, the sampling module 510, the computing module 520, the comparison module 540 and the pulse generation module 550 and figure
Modules structure in embodiment shown in 5 is identical.Difference is, in the present embodiment, the ramp voltage
The first switch S1 of generation module 530 is ground connection, rather than is electrically connected to the fixed voltage source.
Specifically, in the present embodiment, the ramp voltage generation module 530 includes：One first fixed bias electricity
Stream source Ib, a switch control unit 531, a first switch S1 and one first electric capacity C1, reference can be made to Fig. 5；Wherein described first is solid
Determine bias current sources Ib by the first switch S1 electrically, and the first fixed bias current source Ib is electrically connected to institute
State the first electric capacity C1 one end, the other end ground connection of the first electric capacity C1；The switch control unit 531 is used for output one and opened
Control signal is closed, to control the on or off of the first switch S1；When the first switch S1 is turns on, described first
The voltage of electric capacity C1 one end is equal to zero, when the first switch S1 is turns off, Ib pairs of the first fixed bias current source
The first electric capacity C1 is charged, and is produced a no-voltage in one end of the first electric capacity C1 and be starting point and rise oblique
Slope voltage.Wherein, when the switch controlling signal is high level, the first switch S1 is conducting；When the switch control
When signal is low level, the first switch S1 is shut-off.
In the present embodiment, due to current peak reference voltage Vcs_ref and sample reference voltage Vsh_ref with
Primary current peak I pp is directly proportional, ramp voltage Vramp be using no-voltage as starting point, it is and in upward status, until sample reference
Voltage Vsh_ref, now reach sampled point, and then cause in from first switch S1 shutdown moments to the time of the sampled point
Tsh and Ipp are linear, then, can also so realize that sampled point follows peak point current to change automatically, and then can be very big
The difference of sample point secondary side diode voltage drop when ground decreases or even eliminates different loads, so that output voltage precision obtains
Improve.
Above-mentioned adaptively sampled circuit may be embodied in an Isobarically Control chip IC 1, as shown in Figure 8 A and 8 B, and
In other embodiment, the adaptively sampled circuit can also use individual devices to form, and be not comprised in chip IC 1
Portion.
Referring to Fig. 8 A and Fig. 8 B, and Fig. 4-6 are combined, the present invention also provides a kind of primary side feedback constant-voltage system, and it is used
State adaptively sampled circuit.The system includes：One rectifier bridge 820, a filtration module 830, one start power supply module 840, one
Drive module 850, a primary side absorption module 860, a primary current sampling module 870, a voltage sample module 8110, a transformation
Module 880, a secondary output module 890 and a load 8100.Wherein, the input of the rectifier bridge 820 electrically connects with city,
For being direct current by AC rectification, and it is sent to the filtration module 830；The filtration module 830 is used for direct current
It is filtered；The startup power supply module 840 is connected with the filtration module 830, for starting the drive module 850,
And powered to the drive module 850；The drive module 850 is connected with the primary side absorption module 860, for carrying out perseverance
Voltage-controlled system, wherein the drive module 850 includes an Isobarically Control chip IC 1 and a FET Q1, the Isobarically Control core
Piece IC1 includes a constant-voltage control circuit 900, and the constant-voltage control circuit 900 includes above-mentioned adaptively sampled circuit and a ring
Road control module 8120 (referring to Fig. 8 B)；The primary side absorption module 860 is used for the FET for limiting the drive module 850
The ceiling voltage of (FET) drain electrode when off；The primary current sampling module 870 and the drive module
850 connections, for obtaining primary side winding electric current；The voltage changing module 880 is connected with the primary side absorption module 860, for original
The mutual conversion of voltage x current in, secondary, auxiliary between winding；The secondary output module 890 is used to export a secondary
The voltage of winding loads 8100 to described；The voltage sample module 8110 is connected to the drive module 850, for obtaining
The demagnetization time internal feedback voltage in one cycle, and it is sent to the adaptively sampled circuit of the drive module 850.
Each module of primary side feedback constant-voltage system or the structural relation of circuit will be described in detail below.
In the present embodiment, the rectifier bridge 820 includes：First diode D1, the second diode D2, the 3rd diode D3
With the 4th diode D4；The the first diode D1 and the 3rd diode D3 of series connection and second diode connected
D2 and the 4th diode D4 is in parallel.The negative pole of the first diode D1 and the second diode D2 negative pole electrically connect, institute
The positive pole of the positive pole and the second diode D2 of stating the first diode D1 is respectively electrically connected to the negative of the 3rd diode D3
Pole and the negative pole of the 4th diode D4, the positive pole of the 3rd diode D3 and the positive pole of the 4th diode D4 are electrically connected
Connect and be grounded.
The filtration module 830 includes：One second electric capacity C2, the second electric capacity C2 and second diode connected
D2 and the 4th diode D4 is in parallel.That is, one end of the second electric capacity C2 is electrically connected to the second diode C2's
Negative pole, the other end of the second electric capacity C2 are electrically connected to the positive pole of the 4th diode D4.
The startup power supply module 840 includes：One starts resistance Rst, one the 3rd electric capacity C3 and one the 6th diode D6；Institute
State and start resistance Rst and the 3rd electric capacity C3 common connecting point and be respectively electrically connected to the drive module 850 and described the
Six diode D6 negative pole；The other end ground connection of the 3rd electric capacity C3；The other end for starting resistance Rst is electrically connected to institute
State one end of filtration module 830.The positive pole of the 6th diode D6 is electrically connected to sample coil (not marked in figure).
The drive module 850 includes：One Isobarically Control chip IC 1 and a FET Q1.The Isobarically Control chip
IC1 can include constant-voltage control circuit 900, as shown in Figure 8 A.The VCC pin of the Isobarically Control chip IC 1 is electrically connected to institute
State the negative pole for the 6th diode D6 for starting power supply module 840, the GATE pins electrical connection of the Isobarically Control chip IC 1
To the grid of the FET Q1, the FB pins of the Isobarically Control chip IC 1 are electrically connected to the voltage sample module
8110, the CS pins of the Isobarically Control chip IC 1 are electrically connected to the primary current sampling module 870, the Isobarically Control
The GND pin ground connection of chip IC 1；The drain electrode of the FET Q1 is electrically connected to the primary side absorption module 860, the field effect
Should pipe Q1 source electrode be electrically connected to the primary current sampling module 870.The constant-voltage control circuit 900 includes above-mentioned adaptive
Answer sample circuit and a loop back control module 8120.Wherein, the loop back control module 8120 is used to receive described adaptively to adopt
The narrow pulse signal of sample circuit, and feedback voltage signal is carried out sampling holding and error using the narrow pulse signal and put
Greatly, while the FET Q1 of the drive module 850 grid is controlled, to form the control of the voltage close loop of whole loop, entered
And cause the sampling time automatic follow current peak change of the primary side feedback constant-voltage system and change.
The primary side absorption module 860 includes：One the 4th resistance R4, one the 5th electric capacity C5, one the 5th diode D5；It is described
Connected again with the 5th diode D5 after 5th electric capacity C5 is in parallel with the 4th resistance R4.The one of the 4th resistance R4
End is electrically connected to one end of the startup resistance Rst, and the other end is electrically connected to the negative pole of the 5th diode D5.Described 5th
Diode D5 positive pole is electrically connected to the drain electrode of the FET of the drive module 850.
The primary current sampling module 870 includes：One sampling resistor Rcs, for obtaining primary side winding electric current.It is described to adopt
Sample resistance Rcs one end is electrically connected to the CS pins of the Isobarically Control chip IC 1 of the drive module 850, the sampling resistor
Rcs other end ground connection.
The voltage changing module 880 includes：Primary coil, secondary coil, sample coil (not marked in figure) and iron core T1.
The secondary output module 890 includes：One the 7th diode D7 and one the 4th electric capacity C4；The 7th diode D7
Connected with the 4th electric capacity C4, the 4th electric capacity C4 is in parallel with the load 8100.That is, the 7th diode
D7 negative pole is electrically connected to one end of the 4th electric capacity C4.
The voltage sample module 8110 includes：One 3rd resistor R3 and one the 4th resistance R4；The 3rd resistor R3 and
The common connecting point of the 4th resistance R4 is electrically connected to the FB pins of the Isobarically Control chip IC 1 of the drive module 850；Institute
The other end for stating 3rd resistor R3 is electrically connected to the startup power supply module 840；The other end ground connection of the 4th resistance R4.
Referring to Fig. 9, the loop back control module 8120 may include that a second switch S2, one the 6th electric capacity C6, an error are put
Big device (abbreviation EA), a PFM/PWM modulators.The loop back control module 8120 is described narrow after narrow pulse signal is received
Pulse signal carries out sampling holding to feedback voltage signal, after error enhanced processing, feeds back to the grid of the FET Q1
Pole (as shown in Figure 8 A), so as to form voltage close loop control, and then cause the sampling time of the primary side feedback constant-voltage system
Automatic follow current peak change and change.
In the present embodiment, the constant-voltage control circuit 900 can further comprise：One demagnetization detection module 8130, one
The reference voltage generation module 8150 of load current modular converter 8140 and one；Wherein, the demagnetization detection module 8130 is connected to
The voltage sample module 8110, to obtain the demagnetization time；The load current modular converter 8140 is connected to the demagnetization
Detection module 8130, to the relation according to the demagnetization time and work period, to generate the ratio for being proportional to load current
Voltage；The reference voltage generation module 8150 is connected to the load current modular converter 8140, for according to ratio-voltage
Current peak reference voltage is produced, and is sent to the peak reference voltage generation module of the adaptively sampled circuit.The perseverance
The input signal for pressing control circuit 900 is the FB signals of FB pins and the CS of CS pins by the Isobarically Control chip IC 1
Signal, the output signal of the constant-voltage control circuit 900 are to be believed by the GATE of the GATE pins of the Isobarically Control chip IC 1
Number.
In the present embodiment, detected and demagnetized by FB pins, obtain demagnetization time Tdemag, then, by the time of demagnetizing
The ratio-voltage Vload for being proportional to load current is produced with work period Tsw relation, is produced further according to ratio-voltage Vload
Current peak reference voltage Vcs_ref.Then, according to existing known equation Vcs_ref=Ipp*Rcs, it is known that current peak is joined
Examine voltage Vcs_ref and be proportional to primary current peak I pp.
According to described above, ramp voltage Vramp be using the voltage equal with the voltage of the fixed voltage source as starting point,
And it is in upward status, until sample reference voltage Vsh_ref, now reaches sampled point, and then to turn off from first switch S1
Tsh and Ipp is linear in moment to the time of the sampled point, can also then realize sampled point and follow peak value automatically
Curent change, so when can greatly decrease or even eliminate different loads sample point secondary side diode (D7) voltage drop it
Difference, so that output voltage precision is improved.
In addition, it is above-mentioned adaptively using sample circuit in addition to applied to primary side feedback constant-voltage system, it can also apply
Such as switch power supply system (not shown).The switch power supply system may include adaptively sampled circuit and loop control mould
Block, the loop back control module are used to receive the narrow pulse signal that the adaptively sampled circuit is exported, and described in utilization
Feedback voltage signal is carried out sampling holding narrow pulse signal and error is amplified, and to realize the control of whole loop, and then causes
The sampling time automatic follow current peak change of the switch power supply system and change.
Described above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be regarded as
Protection scope of the present invention.
Claims (14)
- A kind of 1. adaptively sampled circuit, it is characterised in that including：One peak reference voltage generation module, a computing module, one Ramp voltage generation module, a comparison module, a pulse generation module；Wherein,The peak reference voltage generation module is used to generate a current peak reference voltage；The computing module is connected with the peak reference voltage generation module, for the current peak reference voltage to be carried out Scale operation, and a sample reference voltage is exported to the comparison module；The ramp voltage generation module is used to produce a ramp voltage, and exports to the comparison module；The comparison module is used for by the sample reference voltage compared with the ramp voltage, when the ramp voltage is big When the sample reference voltage, the sample identification signal of a high level is exported, when the ramp voltage is less than or equal to institute When stating sample reference voltage, a low level sample identification signal is exported；The pulse generation module is used to receive sample identification signal, and narrow in the rising edge of sample identification signal, generation one Pulse signal so that using adaptively sampled circuit switch power supply system sampling time automatic follow current peak change and Change.
- 2. adaptively sampled circuit according to claim 1, it is characterised in that the computing module includes：One computing is put Big device, a first resistor and a second resistance；The first input end of the operational amplifier receives the peak reference voltage life Into the current peak reference voltage of module, the second input of the operational amplifier is respectively electrically connected to one end of first resistor With one end of second resistance；The other end of the first resistor is electrically connected to the output end of the operational amplifier；Described second The other end ground connection of resistance.
- 3. adaptively sampled circuit according to claim 1, it is characterised in that the current peak reference voltage with it is described The proportional amplification relation of sample reference voltage.
- 4. adaptively sampled circuit according to claim 1, it is characterised in that the current peak reference voltage with it is described The proportional diminution relation of sample reference voltage.
- 5. adaptively sampled circuit according to claim 1, it is characterised in that the ramp voltage generation module includes： One first fixed bias current source, a switch control unit, a first switch, a fixed voltage source and one first electric capacity；Wherein The first fixed bias current source is electrically connected to the fixed voltage source by the first switch, and described first fixes partially Put one end that current source is electrically connected to first electric capacity, the other end ground connection of first electric capacity；The switch control unit For exporting a switch controlling signal, to control the on or off of the first switch；When the first switch is turns on, The voltage of one end of first electric capacity is equal to the voltage of the fixed voltage source, described when the first switch is turns off First fixed bias current source is charged to first electric capacity, and first electric capacity one end produce one with it is described The voltage that the voltage of fixed voltage source is equal is starting point and the ramp voltage of rising.
- 6. adaptively sampled circuit according to claim 5, it is characterised in that when the switch controlling signal is high level When, the first switch is conducting；When the switch controlling signal is low level, the first switch is shut-off.
- 7. adaptively sampled circuit according to claim 1, it is characterised in that the ramp voltage generation module includes： One first fixed bias current source, a switch control unit, a first switch and one first electric capacity；Wherein described first fixes partially Current source is put by the first switch electrically, and the first fixed bias current source is electrically connected to first electric capacity One end, first electric capacity the other end ground connection；The switch control unit is used to export a switch controlling signal, with control The on or off of the first switch；When the first switch is turns on, the voltage of one end of first electric capacity is equal to Zero, when the first switch is turns off, the first fixed bias current source is charged to first electric capacity, and It is starting point and the ramp voltage risen that one end of first electric capacity, which produces a no-voltage,.
- 8. adaptively sampled circuit according to claim 7, it is characterised in that when the switch controlling signal is high level When, the first switch is conducting；When the switch controlling signal is low level, the first switch is shut-off.
- 9. adaptively sampled circuit according to claim 1, it is characterised in that the comparison module includes：One comparator, For compared with the ramp voltage, the sample reference voltage to be exported into the sampling mark of varying level according to comparative result Know signal.
- 10. a kind of printed circuit board (PCB), it is characterised in that the printed circuit board (PCB) includes any one of claim 1-9 items institute The adaptively sampled circuit stated.
- 11. a kind of primary side feedback constant-voltage system, it is characterised in that start power supply mould including a rectifier bridge, a filtration module, one Block, a drive module, a primary side absorption module, a primary current sampling module, a voltage sample module, a voltage changing module, one Secondary output module and a load；WhereinThe input of the rectifier bridge electrically connects with city, for being direct current by AC rectification, and is sent to the filtering mould Block；The filtration module is used to be filtered direct current；The startup power supply module is connected with the filtration module, for starting the drive module, and gives the driving Module for power supply；The drive module is connected with the primary side absorption module, for carrying out Isobarically Control, wherein the drive module includes One Isobarically Control chip and a FET, the Isobarically Control chip are included described in any one of claim 1-9 items Adaptively sampled circuit and a loop back control module；The primary side absorption module is used to limit the ceiling voltage that the FET of the drive module drains when off；The primary current sampling module is connected with the drive module, for obtaining primary side winding electric current；The voltage changing module is connected with the primary side absorption module, for the voltage x current between primary side, secondary, auxiliary side winding Mutual conversion；The voltage that the secondary output module is used to export a vice-side winding is to the load；The voltage sample module is connected to the drive module, for obtaining the demagnetization time internal feedback voltage in a cycle, And it is sent to the adaptively sampled circuit of the drive module；The loop back control module is used for the narrow pulse signal for receiving the adaptively sampled circuit, and utilizes the burst pulse Feedback voltage signal is carried out sampling holding signal and error is amplified, while controls the grid of the FET of the drive module Pole, with formed the voltage close loop of whole loop control, and then cause the primary side feedback constant-voltage system sampling time automatically with Change with current peak and change.
- 12. primary side feedback constant-voltage system according to claim 11, it is characterised in that the Isobarically Control chip is further Including：One demagnetization detection module, a load current modular converter and a reference voltage generation module；Wherein,The demagnetization detection module is connected to the voltage sample module, to obtain the demagnetization time；The load current modular converter is connected to the demagnetization detection module, to according to the demagnetization time and work period Relation, the ratio-voltage of load current is proportional to generation；The reference voltage generation module is connected to the load current modular converter, for producing current peak according to ratio-voltage It is worth reference voltage, and is sent to the peak reference voltage generation module of the adaptively sampled circuit.
- 13. primary side feedback constant-voltage system according to claim 12, it is characterised in that when loading different, pass through setting First electric capacity of the current value in the fixed bias current source in the adaptively sampled circuit, the ramp voltage generation module The resistance value of the first resistor and second resistance of capacitance and the computing module, so that in the secondary output module The difference of the voltage drop of seven diodes is zero.
- 14. a kind of switch power supply system, it is characterised in that the switch power supply system includes any one of claim 1-9 Described adaptively sampled circuit and a loop back control module, the loop back control module are used to receive the adaptively sampled electricity The narrow pulse signal that road is exported, and feedback voltage signal is carried out sampling holding and error using the narrow pulse signal and put Greatly, to realize the control of whole loop, and then the sampling time automatic follow current peak value of the switch power supply system is become Change and change.
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| CN106533205B (en) * | 2016-11-01 | 2018-10-23 | 东南大学 | A method of primary side feedback flyback sourse is improved in pressure constant state down-sampling precision |
| CN106501575B (en) * | 2016-11-04 | 2023-07-11 | 上海晶丰明源半导体股份有限公司 | Self-adaptive sampling circuit, sampling method, controller and power supply conversion device |
| CN108347181B (en) * | 2017-01-25 | 2020-02-07 | 芯好半导体(成都)有限公司 | Power supply conversion device |
| CN108448895B (en) * | 2018-02-13 | 2020-12-08 | 昂宝电子（上海）有限公司 | Analog demagnetization sampling method and system for output sampling of switching power supply |
| CN108696279B (en) * | 2018-04-18 | 2022-03-25 | 西安电子科技大学 | Converter for converting voltage signal to time signal |
| CN108732411B (en) * | 2018-07-27 | 2023-10-27 | 上海艾为电子技术股份有限公司 | Self-adaptive sampling circuit and switch charging chip thereof |
| CN110661501B (en) * | 2019-08-29 | 2021-09-24 | 电子科技大学 | Automatic locking circuit for setting quiescent point of power amplifier |
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| CN112865548B (en) * | 2021-03-29 | 2024-06-14 | 上海新进芯微电子有限公司 | Switching power supply and feedback voltage sampling control circuit thereof |
| CN113746347B (en) * | 2021-11-04 | 2022-02-22 | 深圳市力生美半导体股份有限公司 | Flyback switching power supply and sampling control circuit, sampling control method and chip thereof |
| CN114924519B (en) * | 2022-07-18 | 2022-12-27 | 浙江芯昇电子技术有限公司 | Load stabilizing system and method |
| CN116131577B (en) * | 2023-02-16 | 2023-10-17 | 西安致芯微电子有限公司 | Sampling control system, method, controller and primary side feedback AC/DC converter |
| CN117214674B (en) * | 2023-11-07 | 2024-01-30 | 无锡硅动力微电子股份有限公司 | Test system for testing working state of PSR integrated circuit |
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